Memory system and read reclaim method thereof

ABSTRACT

A memory system includes a nonvolatile memory device including a first memory area formed of memory blocks which store n-bit data per cell and a second memory area formed of memory blocks which store m-bit data per cell, where n and m are different integers, and a memory controller configured to control the nonvolatile memory device. The memory controller is configured to execute a read operation, and to execute a read reclaim operation in which valid data of a target memory block of the second memory area is transferred to one or more memory blocks of the first memory area, the target memory block selected during the read operation. The read reclaim operation is processed as complete when all the valid data of the target memory block is transferred to the one or more memory blocks of the first memory area.

CROSS-REFERENCE TO RELATED APPLICATIONS

A claim for priority under 35 U.S.C. §119 is made to Korean PatentApplication No. 10-2012-0110859 filed Oct. 5, 2012, in the KoreanIntellectual Property Office, the entire contents of which are herebyincorporated by reference.

BACKGROUND

The inventive concepts described herein relate to semiconductor memorydevices, and more particularly, the inventive concepts relate to memorysystems including nonvolatile memory and to read reclaim methodsexecuted by memory systems including nonvolatile memory.

Semiconductor memories constitute a vital microelectronic component ofdigital logic system design, such as computers and microprocessor-basedapplications ranging from satellites to consumer electronics. Advancesin the fabrication of semiconductor memories including processenhancements and technology developments through scaling for higherdensities and faster operating speeds help establish performancestandards for other digital logic families.

One category of semiconductor memory is volatile random access memory(RAM). In volatile RAM devices, logic information is typically storedeither by setting up the logic state of a bistable flip-flop such as ina static random access memory (SRAM), or through the charging of acapacitor as in a dynamic random access memory (DRAM). In either case,the devices are considered volatile in that stored data is lost if thesupply of power thereto is interrupted.

Another category of semiconductor memory is non-volatile memory whichretains stored data even when the supply of power is interrupted.Examples include Mask Read-Only Memory (MROM), Programmable Read-OnlyMemory (PROM), Erasable Programmable Read-Only Memory (EPROM), andElectrically Erasable Programmable Read-Only Memory (EEPROM). The datastored in non-volatile memory may be permanent or reprogrammable,depending upon the fabrication technology used. In addition,non-volatile memories may be used for program and microcode storage in awide variety of applications in the computer, avionics,telecommunications, and consumer electronics industries. A combinationof single-chip volatile and non-volatile memory storage modes is alsoavailable in devices such as non-volatile SRAM (nvSRAM) for use insystems that require fast, programmable non-volatile memory. Inaddition, dozens of special memory architectures have evolved whichcontain additional logic circuitry to optimize their performance forapplication-specific tasks.

Among the previous given examples of non-volatile memory, MROM, PROM,and EPROM are not capable of being erased and then written to by acorresponding system itself, and it is thus difficult or impossible forgeneral users to update stored contents. On the other hand, EEPROM iscapable of being electrically erased and then written at a system level.Applications of EEPROM have therefore expanded to auxiliary memory andsystem programming where continuous updates are needed. An example ofthis is the widely adopted flash memory.

SUMMARY

One aspect of embodiments of the inventive concept is directed toprovide a memory system which includes a nonvolatile memory deviceincluding a first memory area formed of memory blocks which store n-bitdata per cell and a second memory area formed of memory blocks whichstore m-bit data per cell, where n and m are different integers, and amemory controller configured to control the nonvolatile memory device.The memory controller is configured to execute a read operation, and toexecute a read reclaim operation in which valid data of a target memoryblock of the second memory area is transferred to one or more memoryblocks of the first memory area, the target memory block selected duringthe read operation. The read reclaim operation is processed as completewhen all the valid data of the target memory block is transferred to theone or more memory blocks of the first memory area.

Another aspect of embodiments of the inventive concept is directed toprovide a read reclaim method of a memory controller which controls anonvolatile memory device including first memory blocks which storen-bit data per cell and second memory blocks which store m-bit data percell, where n and m are different integers. The method includesidentifying a memory block among the second memory blocks as a target ofa read reclaim operation, and executing the read reclaim operation bytransferring valid data of the memory block identified as a target ofthe read reclaim operation to one or more memory blocks among the firstmemory blocks. The read reclaim operation is processed as complete whenall the valid data is transferred to the one or more memory blocks amongthe first memory blocks.

Still another aspect of embodiments of the inventive concept is directedto provide an operating method of a memory controller which controls anonvolatile memory device including first memory blocks which storen-bit data per cell and second memory blocks which store m-bit data percell, where n and m are different integers. The method includes storingqueue information indicating that a second memory block is a targetmemory block of a read reclaim operation when an error of data read fromthe second memory block exceeds a reference, and upon a host request,determining whether the target memory block exists based on the queueinformation. The method further includes programming valid data of thetarget memory block in at least one or more memory blocks among thefirst memory blocks when the target memory block is determined to exist,and programming data stored at the at least one or more memory blocksamong the first memory blocks in a memory block among the second memoryblocks at a garbage collection operation. The read reclaim operation isprocessed as completed when all the valid data of the target memoryblock is programmed in the at least one or more memory blocks among thefirst memory blocks.

BRIEF DESCRIPTION OF THE FIGURES

The above and other objects and features will become apparent from thedetailed description that follows, with reference to the accompanyingfigures, wherein like reference numerals refer to like parts throughoutthe various figures unless otherwise specified.

FIG. 1 is a diagram schematically illustrating a program operationexecuted in a reprogramming technique according to an embodiment of theinventive concept.

FIG. 2 is a block diagram schematically illustrating a memory systemaccording to an embodiment of the inventive concept.

FIG. 3 is a block diagram schematically illustrating an example of amemory controller shown in FIG. 2.

FIG. 4 is a block diagram schematically illustrating an example of anonvolatile memory device shown in FIG. 2.

FIG. 5 is a block diagram schematically illustrating an example of amemory cell array shown in FIG. 4.

FIGS. 6A to 6D are diagrams for describing various implementations offirst and second memory areas of a multi-bit memory device according toembodiments of the inventive concept.

FIG. 7 is a flow chart illustrating a read method of a memory systemaccording to an embodiment of the inventive concept.

FIGS. 8A and 8B are diagrams illustrating a read reclaim operationaccording to an embodiment of the inventive concept.

FIG. 9 is a diagram illustrating an example in which data of SLC blocksgenerated via a read reclaim operation is stored at a TLC block.

FIG. 10 is a flow chart illustrating a read method of a memory systemaccording to another embodiment of the inventive concept.

FIG. 11 is a flow chart illustrating a read method of a memory systemaccording to still another embodiment of the inventive concept.

FIG. 12 is a block diagram schematically illustrating a read reclaimtechnique of a memory system according to an embodiment of the inventiveconcept.

FIG. 13 is a block diagram schematically illustrating a computing systemaccording to an embodiment of the inventive concept.

FIG. 14 is a block diagram schematically illustrating a solid statedrive according to an embodiment of the inventive concept.

FIG. 15 is a block diagram schematically illustrating a storage systemincluding a plurality of solid state drives shown in FIG. 14.

FIG. 16 is a block diagram schematically illustrating a storage serverincluding a plurality of solid state drives shown in FIG. 14.

FIG. 17 is a block diagram schematically illustrating a moviNAND® deviceaccording to an embodiment of the inventive concept.

FIG. 18 is a block diagram schematically illustrating a communicationdevice according to an embodiment of the inventive concept.

FIG. 19 is a diagram schematically illustrating systems to which a datastorage device according to embodiments of the inventive concept isapplied.

FIG. 20 is a block diagram schematically illustrating a memory cardaccording to an embodiment of the inventive concept.

FIG. 21 is a block diagram schematically illustrating a digital stillcamera according to an embodiment of the inventive concept.

FIG. 22 is a diagram schematically illustrating various systems to whicha memory card in FIG. 21 is applied.

DETAILED DESCRIPTION

Embodiments will be described in detail with reference to theaccompanying drawings. The inventive concept, however, may be embodiedin various different forms, and should not be construed as being limitedonly to the illustrated embodiments. Rather, these embodiments areprovided as examples so that this disclosure will be thorough andcomplete, and will fully convey the concept of the inventive concept tothose skilled in the art. Accordingly, known processes, elements, andtechniques are not described with respect to some of the embodiments ofthe inventive concept. Unless otherwise noted, like reference numeralsdenote like elements throughout the attached drawings and writtendescription, and thus descriptions will not be repeated. In thedrawings, the sizes and relative sizes of layers and regions may beexaggerated for clarity.

It will be understood that, although the terms “first”, “second”,“third”, etc., may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another region, layer or section. Thus, a firstelement, component, region, layer or section discussed below could betermed a second element, component, region, layer or section withoutdeparting from the teachings of the inventive concept.

Spatially relative terms, such as “beneath”, “below”, “lower”, “under”,“above”, “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “below” or “beneath”or “under” other elements or features would then be oriented “above” theother elements or features. Thus, the exemplary terms “below” and“under” can encompass both an orientation of above and below. The devicemay be otherwise oriented (rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein interpretedaccordingly. In addition, it will also be understood that when a layeris referred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the inventiveconcept. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Also, the term “exemplary” is intended to referto an example or illustration.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to”, “coupled to”, or “adjacent to” anotherelement or layer, it can be directly on, connected, coupled, or adjacentto the other element or layer, or intervening elements or layers may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected to”, “directly coupled to”, or “immediatelyadjacent to” another element or layer, there are no intervening elementsor layers present.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this inventive concept belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present specification and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

As the number of data bits stored at each memory cell increases (or, asthe number of pages (or, page data) corresponding to each word lineincreases), various programming techniques may have been proposed. Forexample, an on-chip buffer program method may be applied to a memorysystem including a multi-bit memory device. It is possible to reduce asize of a buffer memory included in a memory controller of the memorysystem by using the on-chip buffer program method. The on-chip bufferprogram method may include programming data temporarily stored at thebuffer memory of the memory controller at a first memory area of amulti-bit memory device and programming data stored at the first memoryarea of the multi-bit memory device at a second memory area of themulti-bit memory device. Programming data temporarily stored at thebuffer memory at the first memory area of the multi-bit memory devicemay be referred to as a buffer program operation, and programming datastored at the first memory area of the multi-bit memory device at thesecond memory area of the multi-bit memory device may be referred to asa main program operation. That is, the on-chip buffer program method mayinclude a buffer program operation and a main program operation. Themulti-bit memory device may further comprise other memory areas otherthan the first and second memory areas.

In example embodiments, the buffer program operation may be performedwhen data corresponding to a minimum program unit of the first memoryarea is gathered at the buffer memory of the memory controller. The mainprogram operation may be performed when data corresponding to a minimumprogram unit of the second memory area is gathered at the first memoryarea of the multi-bit memory device or when a usable storage space ofthe first memory area is insufficient. Herein, data corresponding to theminimum program unit of the first memory area may be a page of data, anddata corresponding to the minimum program unit of the second memory areamay be plural pages of data. The number of pages constituting the pluralpages may be decided according to a bits-per-cell number. For example,in the event that a bits-per-cell number is 3 (i.e., 3 bits of data arestored in each cell), data corresponding to the minimum program unit ofthe second memory area may be 3-page data. It is understood that theminimum program units of the first and second memory areas are notlimited to this disclosure. With the above description, data of thebuffer memory may be programmed at the first memory area of themulti-bit memory device whenever data corresponding to the minimumprogram unit of the first memory area is gathered at the buffer memory.Thus, it is possible to reduce a size of the buffer memory.

In a memory system adopting the on-chip buffer program method, the mainprogram operation may be performed using various programming techniques.For example, the main program operation may be carried out according toa reprogramming technique. Below, the main program operation using thereprogramming technique will be more fully described with reference toFIG. 1.

FIG. 1 is a diagram schematically illustrating a program operationexecuted in accordance with a reprogramming technique according to anembodiment of the inventive concept. Referring to FIG. 1, there isillustrated an example in which 3-bit data (or, 3-page data formed ofLSB page data, CSB page data, and MSB page data) is programmed accordingto a reprogramming technique. However, 3-bit data is merely given as anexample, and the reprogramming technique is not limited to 3-bit data.

In the example of FIG. 1, the reprogramming technique may include firstprogramming, second programming and third programming, which will bemore fully described.

At the first programming, respective memory cells may be maintained inan erase state E or programmed from the erase state E to one of programstates E and P11 to P17. Herein, the eight states E and P11 to P17, asillustrated in FIG. 1, may be adjacent to one another without readmargin interposed therebetween. That is, 3-bit data may be considered asbeing roughly programmed at the first programming. The 3-bit data may bedata programmed at a first memory area via a buffer program operation,and may be read from the first memory area at the first programming.

In example embodiments, the first programming may be performed inaccordance an Incremental Step Pulse Programming (ISPP) technique inwhich a program voltage is incremented at each iteration of a programloop.

In example embodiments, the first programming may include a verificationoperation. At the verification operation of the first programming, atleast one program state may be verified. For example, at the firstprogramming, even numbered program states P12, P14, and P16 may beverified, while odd number program states P11, P13, and P15, and P17 maynot be verified. In other words, in this example, the first programmingmay be completed when the program states P12, P14, and P16 areverify-passed.

The second programming may be carried out to reprogram the 3-bit dataprogrammed at the first programming, i.e., to reprogram the firstprogrammed states P11 to P17 to states P21 to P27 having thresholdvoltage distributions of higher density. Here, the states P21 to P27, asillustrated in FIG. 1, may be adjacent to one another with predeterminedread margin interposed therebetween. As described above, 3-bit data usedat the second programming may be the same as that used at the firstprogramming, and may be read from the first memory area. As illustratedin FIG. 1, the first-programmed state P11 may be reprogrammed to a stateP21 at the second programming. As a result, a threshold voltagedistribution corresponding to the state P21 may become narrower in widththan that corresponding to the state P11. In other words, a verificationvoltage VR21 for verifying the second-programmed state P21 may be higherthan a verification voltage VR11 for verifying the first-programmedstate P11.

In example embodiments, the second programming may be executed accordingto the ISPP technique.

In example embodiments, the second programming may include averification operation. All program states may be verified at averification operation of the second programming. That is, the secondprogramming may be completed when all program states P21 to P27 areverify-passed.

The third programming may be carried out to reprogram the 3-bit dataprogrammed at the second programming, i.e., to reprogram the secondprogrammed states P21 to P27 to denser states P31 to P37. Herein, thestates P31 to P37, as illustrated in FIG. 1, may be adjacent to oneanother with a predetermined read margin interposed therebetween whichis larger than that of the second programming. As described above, 3-bitdata used at the third programming may be equal to that used at thefirst/second programming, and may be read from the first memory area. Asthe third programming is executed, the second-programmed state P21 maybe reprogrammed to a state P31 at the third programming. As a result, athreshold voltage distribution corresponding to the third-programmedstate P31 may be narrower in width than that corresponding to thesecond-programmed state P21. In other words, a verification voltage VR31for verifying the third-programmed state P31 may be higher than averification voltage VR21 for verifying the second-programmed state P21.

In example embodiments, the third programming may be executed inaccordance with the ISPP technique.

In example embodiments, all program states may be verified at averification operation of the third programming. That is, the thirdprogramming may be completed when all program states P31 to P37 areverify-passed.

As previously mentioned, the inventive concept is not limited to theexample of 3-bit data being programmed at the first programming. Theinventive concept is applicable to an example in which 2-bit data isprogrammed at the first programming. After 2-bit data is firstprogrammed, second programming may be executed to program 1-bit data.Afterwards, third programming may be performed to obtain targetthreshold voltage distributions. A related program technique isdisclosed in U.S. Patent Publication No. 2011-0222342, the entirecontents of which are hereby incorporated by reference.

A 3-bit program operation illustrated in FIG. 1 may be performed in a3-step reprogramming technique. However, the inventive concept is notlimited thereto. In the inventive concept, a program operation executedin a reprogramming technique may include three programming operationsexecuted to narrow a threshold voltage distribution corresponding to adata value to be stored (in other words, to finely form a thresholdvoltage distribution).

FIG. 2 is a block diagram schematically illustrating a memory systemaccording to an embodiment of the inventive concept.

Referring to FIG. 2, a memory system 1000 according to an embodiment ofthe inventive concept may include a memory controller 1200 and anonvolatile memory device 1400 as a multi-bit memory device. The memorycontroller 1200 may be configured to control the nonvolatile memorydevice 1400 according to an external request (e.g., a write request, aread request, etc). The memory controller 1200 may be configured tocontrol the nonvolatile memory device 1400 according to an internalrequest (e.g., an operation associated with sudden power-off, awear-leveling operation, a read reclaim operation, etc.) and without anexternal request. An operation corresponding to an internal request ofthe memory controller 1200 may be executed within a timeout period of ahost after a host request is processed. Alternatively, an operationcorresponding to an internal request of the memory controller 1200 maybe executed within an idle time of the memory controller 1200. Thenonvolatile memory device 1400 may operate responsive to the control ofthe memory controller 1200, and may be used as a type of storage mediumwhich stores data information. The storage medium may be formed of oneor more memory chips. The nonvolatile memory device 1400 may communicatewith the memory controller 1200 via one or more channels. Thenonvolatile memory device 1400 may include a NAND flash memory device,for example.

The memory system 1000 may use the above-described on-chip bufferprogram technique. As will be described later, the nonvolatile memorydevice 1400 may include a memory cell array having a first memory areaand a second memory area. In example embodiments, a bits-per-cell numberof the first memory area may be less than a bits-per-cell number of thesecond memory area. For example, the first memory area may be formed ofmemory blocks which store 1-bit data per cell, and the second memoryarea may be formed of memory blocks which store 3-bit data per cell.However, the bits-per-cell number of each of the first and second memoryareas is not limited to this example. The memory controller 1200 mayperform a read reclaim operation according to whether the number oferror bits of data read from one of memory blocks in the second memoryarea exceeds a reference. With the read reclaim operation of theinventive concept, data stored at a memory block in the second memoryarea may be moved to memory blocks in the first memory area, and not toa memory block in the second memory area. In the case of the inventiveconcept, when data stored at a memory block in the second memory area ismoved to memory blocks in the first memory area, a read reclaimoperation associated with the memory block in the second memory area maybe ended. This will be more fully described later.

FIG. 3 is a block diagram schematically illustrating an example of amemory controller shown in FIG. 2. Referring to FIG. 3, a memorycontroller 1200 may include a host interface 1210 as a first interface,a memory interface 1220 as a second interface, a CPU 1230, a buffermemory 1240, and an error detecting and correcting circuit (ECC) 1250.

The host interface 1210 may be configured to interface with an externaldevice (for example, a host), and the memory interface 1220 may beconfigured to interface with a nonvolatile memory device 1400illustrated in FIG. 2. The CPU 1230 may be configured to control anoverall operation of the controller 1200. The CPU 1230 may be configuredto operate firmware such as Flash Translation Layer (FTL), for example.The FTL may perform a variety of functions. For example, the FTL mayinclude a variety of layers performing an address mapping operation, aread reclaim operation, an error correction operation, and so on. Thebuffer memory 1240 may be used to temporarily store data to betransferred from an external device via the host interface 1210 or datato be transferred from the nonvolatile memory device 1400 via the memoryinterface 1220. The buffer memory 1240 may be used to store information(e.g., information indicating source memory blocks needed for a readreclaim operation, address mapping information, etc.) necessary tocontrol the nonvolatile memory device 1400.

The buffer memory 1240 may be formed of DRAM, SRAM, or a combination ofDRAM and SRAM. However, the inventive concept is not limited thereto.The ECC 1250 may be configured to encode data to be stored in thenonvolatile memory device 1400 and to decode data read out from thenonvolatile memory device 1400.

Although not illustrated in figures, the memory controller 1200 mayfurther include a randomizer/de-randomizer which is configured torandomize data to be stored in the nonvolatile memory device 1400 and tode-randomize data read from the nonvolatile memory device 1400. Anexample of a randomizer/de-randomizer is disclosed in U.S. PatentPublication No. 2010/0088574, the entire contents of which are herebyincorporated by reference.

In example embodiments, the host interface 1210 may be formed of one ofcomputer bus standards, storage bus standards, and iFCPPeripheral busstandards, or a combination of two or more standards. The computer busstandards may include S-100 bus, Mbus, Smbus, Q-Bus, ISA, Zorro II,Zorro III, CAMAC, FASTBUS, LPC, EISA, VME, VXI, NuBus, TURBOchannel,MCA, Sbus, VLB, PCI, PXI, HP GSC bus, CoreConnect, InfiniBand, UPA,PCI-X, AGP, PCIe, Intel QuickPath Interconnect, Hyper Transport, and thelike. The storage bus standards may include ST-506, ESDI, SMD, ParallelATA, DMA, SSA, HIPPI, USB MSC, FireWire (1394), Serial ATA, eSATA, SCSI,Parallel SCSI, Serial Attached SCSI, Fibre Channel, iSCSI, SAS, RapidIO,FCIP, etc. The iFCPPeripheral bus standards may include Apple DesktopBus, HIL, MIDI, Multibus, RS-232, DMX512-A, EIA/RS-422, IEEE-1284,UNI/O, 1-Wire, I2C, SPI, EIA/RS-485, USB, Camera Link, External PCIe,Light Peak, Multidrop Bus, and the like.

FIG. 4 is a block diagram schematically illustrating an example of anonvolatile memory device shown in FIG. 2.

A nonvolatile memory device 1400 may be a NAND flash memory device, forexample. However, it is understood that the nonvolatile memory device1400 is not limited to the NAND flash memory device. For example, theinventive concept may be applied to a NOR flash memory device, aResistive Random Access Memory (RRAM) device, a Phase-Change Memory(PRAM) device, a Magnetroresistive Random Access Memory (MRAM) device, aFerroelectric Random Access Memory (FRAM) device, a Spin Transfer TorqueRandom Access Memory (STT-RAM), and the like. Further, the nonvolatilememory device 1400 can be implemented to have a three-dimensional arraystructure. An example of a nonvolatile memory device with thethree-dimensional array structure may be referred to as a vertical NANDflash memory device. The inventive concept may be applied to a ChargeTrap Flash (CTF) memory device including a charge storage layer formedof an insulation film as well as a flash memory device including acharge storage layer formed of a conductive floating gate.

Referring to FIG. 4, the nonvolatile memory device 1400 may include amemory cell array 1410, an address decoder 1420, a voltage generator1430, control logic 1440, a page buffer circuit 14500, and aninput/output interface 1460.

The memory cell array 1410 may include memory cells arranged atintersections of rows (e.g., word lines) and columns (e.g., bit lines).As an example, each memory cell may store 1-bit data or m-bit data asmulti-bit data (m being an integer of 2 or more). The address decoder1420 may be controlled by the control logic 1440, and may performselecting and driving operations on rows (e.g., word lines, a stringselection line(s), a ground selection line(s), a common source line,etc.) of the memory cell array 1410. The voltage generator 1430 may becontrolled by the control logic 1440, and may generate voltages requiredfor each operation such as a high voltage, a program voltage, a readvoltage, a verification voltage, an erase voltage, a pass voltage, abulk voltage, and the like. Voltages generated by the voltage generator1430 may be provided to the memory cell array 1410 via the addressdecoder 1420. The control logic 1440 may be configured to control anoverall operation of the nonvolatile memory device 1400.

The page buffer circuit 1450 may be controlled by the control logic1440, and may be configured to read data from the memory cell array 1410and to drive columns (e.g., bit lines) of the memory cell array 1410according to program data. The page buffer circuit 1450 may include pagebuffers respectively corresponding to bit lines or bit line pairs. Eachof the page buffers may include a plurality of latches. The input/outputinterface 1460 may be controlled by the control logic 1440, and mayinterface with an external device (e.g., a memory controller in FIG. 2).Although not illustrated in FIG. 4, the input/output interface 1460 mayinclude a column decoder configured to select page buffers of the pagebuffer circuit 1450 by a predetermined unit, an input buffer receivingdata, an output buffer outputting data, and so on.

FIG. 5 is a block diagram schematically illustrating an example of amemory cell array shown in FIG. 4.

Referring to FIG. 5, a memory cell array 1410 may include a plurality ofmemory blocks, which are divided into a first memory area 1411 and asecond memory area 1412. Herein, the division of the first and secondmemory areas 1411 and 1412 is made logically, rather than physically.Also, division of the first and second memory areas 1411 and 1412 can bechanged logically. In other words, physical sizes of the first andsecond memory areas 1411 and 1412 can be changed logically under thecontrol of a memory controller 1200. The first memory area 1411 isformed of memory blocks which store n-bit data per cell and the secondmemory area 1412 is formed of memory blocks which store m-bit data percell, where n and m are integers. Also, memory blocks in the firstmemory area 1411 may be programmed in a manner different from memoryblocks in the second memory area 1412, for example, n may be less thanm. For example, memory blocks in the first memory area 1411 may beprogrammed according to a single-bit program technique (hereinafter,referred to as an SLC program technique), and memory blocks in thesecond memory area 1412 may be programmed according to a multi-bitprogram technique (hereinafter, referred to as an MLC/TLC programtechnique) (e.g., the above-described 3-step reprogramming technique).In other words, each memory cell in the first memory area 1411 may store1-bit data (n=1), while each memory cell in the second memory area 1412may store m-bit data (m being an integer of 2 or more). The number ofdata bits stored at each of memory cells in the first memory area 1411may be less that that stored at each of memory cells in the secondmemory area 1412. Herein, it is understood that each memory cell in thefirst memory area 1411 is not limited to store 1-bit data.

As described above, data provided from a memory controller 1200 may beprogrammed at the first memory area 1411 via a buffer program operation.Data for a main program operation may be read out from the first memoryarea 1411, and the read data may be programmed at the second memory area1412 via the main program operation.

FIGS. 6A to 6D are diagrams for describing various combinations of firstand second memory areas of a multi-bit memory device according to anembodiment of the inventive concept. In figures, “BP” indicates bufferprogramming on a first memory area 1411, and “MP” indicates mainprogramming on a second memory area 1412.

As described above, a multi-bit memory device 1400 includes the firstmemory area 1411 and the second memory area 1412. Herein, the first andsecond memory areas 1411 and 1412 may constitute a memory cell array ofthe multi-bit memory device 1400. Although not illustrated in figures,the memory cell array may further include areas such as a meta area, areserved area, and so on. It is understood that areas of the memory cellarray may be divided logically, not physically. This means that suchareas of the memory cell array may be defined according to addressmapping of a memory controller 1200.

Referring to FIG. 6A, in the case of a multi-bit memory device whichstores 3-bit data per cell, the first memory area 1411 may be formed ofmemory cells each storing 1-bit data, and the second memory area 1412may be formed of memory cells each storing 3-bit data. In this case,buffer programming may be executed according to an SLC programtechnique, and main programming may be made according to theabove-described MLC program technique.

Referring to FIG. 6B, in the case of a multi-bit memory device whichstores 4-bit data per cell, the first memory area 1411 may be formed ofmemory cells each storing 1-bit data, and the second memory area 1412may be formed of memory cells each storing 4-bit data. In this case,buffer programming may be executed according to an SLC programtechnique, and main programming may be made according to theabove-described MLC/TLC program technique.

Referring to FIG. 6C, in the case of a multi-bit memory device whichstores 3-bit data per cell, the first memory area 1411 may be formed ofmemory cells each storing 2-bit data, and the second memory area 1412may be formed of memory cells each storing 3-bit data. In this case,buffer programming may be executed according to the above-described orconventional MLC program technique, and main programming may be madeaccording to the above-described MLC/TLC program technique (e.g., areprogram technique).

Referring to FIG. 6D, in the case of a multi-bit memory device whichstores 4-bit data per cell, the first memory area 1411 may be formed ofmemory cells each storing 2-bit data, and the second memory area 1412may be formed of memory cells each storing 4-bit data. In this case,buffer programming may be executed according to the above-described orconventional MLC program technique, and main programming may be madeaccording to the above-described MLC/TLC program technique (e.g., areprogram technique).

In exemplary embodiments, it is understood that defining of the firstand second memory areas 1411 and 1412 illustrated in FIGS. 6A to 6D isnot limited to these examples. For example, if storage medium includedin a memory system is formed of a plurality of multi-bit memory devices,the first and second memory areas 1411 and 1412 can be defined withrespect to the respective multi-bit memory devices. Alternatively, eachof memory cell arrays of one or more multi-bit memory device may bedefined as the first memory area 1411. Each of memory cell arrays of theremaining multi-bit memory devices may be defined as the second memoryarea 1412.

FIG. 7 is a flow chart illustrating a read method of a memory systemaccording to an embodiment of the inventive concept. In the descriptionthat follows, an example is given in which a first memory area 1411 isformed of memory blocks (hereinafter, referred to as SLC blocks) whichstore 1-bit data per cell and a second memory area 1412 is formed ofmemory blocks (hereinafter, referred to as TLC blocks) which store 3-bitdata per cell.

Referring to FIGS. 3, 6A and 7, in operation S110, a memory controller1200 may receive a read request from an external device (e.g., a host).In operation S120, the memory controller 1200 may control a nonvolatilememory device 1400 such that read requested data is output. The readrequested data may be data stored at a TLC block of a second memory area1412, for example. Alternatively, the read requested data may be datastored at an SLC block of a first memory area 1411. In the example ofthis embodiment, the read requested data is data stored at a TLC blockof the second memory area 1412.

In operation S130, while data output from the nonvolatile memory device1400 is transferred to a buffer memory 1240 of the memory controller1200, an ECC circuit 1250 of the memory controller 1200 may perform anerror detecting operation on data output from the nonvolatile memorydevice 1400. At this time, the data output from the nonvolatile memorydevice 1400 may be temporarily stored at the buffer memory 1240 of thememory controller 1200.

In operation S140, whether an error contained in data output from thenonvolatile memory device 1400 is correctable by the ECC circuit 1250may be determined If the error is correctable by the ECC circuit 1250,the method proceeds to operation S150. In operation S150, the errorcontained in the data output from the nonvolatile memory device 1400 maybe corrected by the ECC circuit 1250 to obtain corrected data. Inoperation S160, the corrected data may be stored at the buffer memory1240 and sent to the external device as the read requested data. At thistime, the read operation may be terminated.

Returning to operation S140, an error contained in data output from thenonvolatile memory device 1400 may be considered uncorrectable, forexample, in the case where the number of error bits of the data outputfrom the nonvolatile memory device 1400 exceeds a threshold (e.g., anallowable error bit number of the ECC circuit 1250). In the case ofuncorrectable error at operation S140, the method proceeds to operationS170. In operation S170, the memory controller 1200 may use software toperform an error detecting and correcting operation on the data outputfrom the nonvolatile memory device 1400. That is, even in the case wherethe number of error bits included in the data output from thenonvolatile memory device 1400 exceeds an allowable error bit number ofthe ECC circuit 1250, it may be possible to correct an error containedin the data output from the nonvolatile memory device 1400 using errordetecting and correcting software of the memory controller 1200. Forexample, an error detecting and correcting operation may be performed bya flash translation layer (FTL). In operation S180, it may be determinedwhether the data output from the nonvolatile memory device 1400 has beencorrected by software in operation S170.

If the data output from the nonvolatile memory device 1400 is determinednot to be correctable by software, the method proceeds to operationS190. In operation S190, the memory controller 1200 may process the readoperation requested by the external device as a read fail. For example,a read fail flag may be generated according to any of a variety ofdifferent procedures. At this time, the read method may be terminated.

On the other hand, if the data output from the nonvolatile memory device1400 is determined to have been corrected by software in operation S170,the method proceeds to operation S200. In operation S200, the memorycontroller 1200 may send the corrected data stored at the buffer memory1240 to the external device as the read requested data. At this time,under control of the CPU 1230, information may be stored in a queueindicating that the TLC block storing the read requested data is amemory block that necessitates a read reclaim operation. This will bemore fully described later herein.

In example embodiments, the queue may be formed by a part of the buffermemory 1240, and information stored at the queue may be referenced bythe CPU 1230. To the loss of the queue information due to a suddenpower-off condition, information stored at the queue may also beperiodically stored at the nonvolatile memory device 1400. A readreclaim operation on a TLC block may be performed based on informationstored at the queue. This will be more fully described later herein.

FIGS. 8A and 8B are diagrams for reference in describing a read reclaimoperation according to an embodiment of the inventive concept.

For a variety of reasons, threshold voltage distributions of memorycells may be shifted from an ideal programmed distribution. For example,variations in temperature, multiple read operation iterations, and soon, can cause threshold voltage distribution to shift over time. Thisshift of threshold voltage distributions may cause an increase in thenumber of error bits contained within read data. This is particularlythe case where read margins are low, such in the case of a TLC blockwhich stores 3-bit data per cell. That is, the number of error bitscaused by threshold voltage distributions may further increase multi-bitmemory cells. Thus, a read reclaim operation may be performed to securethe integrity of read data. The read reclaim operation refers to anoperation in which valid data of a TLC block including page data ismoved to a new block. The page data may be determined to beuncorrectable and is thus moved to a new block, or the page data may bedetermined to have a high probability of a later increase in the numberof error bits and is thus moved to a new block. The read reclaimoperation may be performed because a shift of threshold voltagedistributions of memory cells at which page data is stored affectsadjacent memory cells.

Referring to FIG. 8A, a CPU 1230 may select a TLC block being a targetblock of a read reclaim operation of a flash translation layer FTL basedon information stored at a queue. For example, it is assumed that aselected TLC block includes 64 word lines. Therefore, in the case of3-bits-per-cell memory, 192 pages of data may be stored at one TLCblock. In the case that 192 pages of data stored at the selected TLCblock are all valid, there may be required three SLC blocks to move 192pages of data stored at the selected TLC block. 64 pages of data may beread from a TLC block selected to perform a read reclaim operation, andthe 64 pages of read data may be stored at one SLC block SB0 of a firstmemory area 1411 via an ECC circuit 1250 of a memory controller 1200.Then, 64 pages of data may be read from the selected TLC block for theread reclaim operation, and the 64 pages of read data may be stored atone SLC block SB1 of the first memory area 1411 via the ECC circuit 1250of the memory controller 1200. Finally, 64 pages of data may be readfrom the selected TLC block for the read reclaim operation, and the 64pages of read data may be stored at one SLC block SB2 of the firstmemory area 1411 via the ECC circuit 1250 of the memory controller 1200.

Referring to FIG. 8B, in the case that 150 pages of data of 192 pages ofdata stored at the selected TLC block are valid, there may be requiredthree SLC blocks to move 150 pages of data stored at the selected TLCblock. 64 pages of data may be read from a TLC block selected to performa read reclaim operation, and the 64 pages of read data may be stored atone SLC block SB0 of the first memory area 1411 via the ECC circuit 1250of the memory controller 1200. Then, 64 pages of data may be read fromthe selected TLC block for the read reclaim operation, and the 64 pagesof read data may be stored at one SLC block SB1 of the first memory area1411 via the ECC circuit 1250 of the memory controller 1200. Finally, 22pages of data may be read from the selected TLC block for the readreclaim operation, and the 22 pages of read data may be stored at oneSLC block SB2 of the first memory area 1411 via the ECC circuit 1250 ofthe memory controller 1200.

When all valid pages of data stored at a TLC block are moved to thefirst memory area 1411, the CPU 1230 may process the read reclaimoperation of the FTL on the TLC block as being complete. For example,information (indicating a target block of a read reclaim operation)stored at the queue may be changed.

As described above, with the read reclaim operation of the inventiveconcept, valid pages of data of a TLC block being a target block of aread reclaim operation may be moved to SLC blocks of the first memoryarea 1411, and not to a TLC block of a second memory area 1412. If atransfer of data into SLC blocks of the first memory area 1411 iscompleted, a read reclaim operation on a TLC block may be processed ascomplete. In other words, at the read reclaim operation of the inventiveconcept, valid pages of data of a TLC block being a target block of aread reclaim operation may not be moved to a TLC block of the secondmemory block 1412.

In example embodiments, valid pages of data of a TLC block being atarget block of a read reclaim operation may be moved to SLC blocks ofthe first memory area 1411 in a time division manner. For example, apart (e.g., valid pages of data corresponding to a size of an SLC block)of valid pages of data of a TLC block being a target block of a readreclaim operation may be moved to one SLC block. This may be performedwithin a host timeout period after a read or write operation iscompleted whenever the read or write operation is requested by a host. Aread reclaim operation on a TLC block may be completed when all validpages of data of a TLC block are moved to SLC blocks.

In example embodiments, the number of SLC blocks of the first memoryarea 1411 to which valid pages of data of a TLC block being a targetblock of a read reclaim operation is to be moved may be decided in viewof a host timeout period. For example, a number of SLC blocks of thefirst memory area 1411 may be decided in view of the remaining time ofthe timeout period after a write request of a host is processed. Data ofa TLC block being a target block of a read reclaim operation may bemoved to SLC blocks decided at a write request of a host.

Data moved from a TLC block to SLC blocks may be stored at the secondmemory area 1412 via a main program operation. This operation may beperformed at a garbage collection operation. This will be more fullydescribed with reference to FIG. 9.

FIG. 9 is a diagram for reference in describing an example in which dataof SLC blocks generated via a read reclaim operation is stored at a TLCblock.

As described above, a read reclaim operation of the inventive conceptmay be completed when valid pages of data of a TLC block are moved toSLC blocks of a first memory area 1411. One of SLC blocks may include anempty storage space according to the number of valid pages of the TLCblock. For example, Referring to FIGS. 8B and 9, in the case that 150pages of data of 192 pages of data stored at a selected TLC block arevalid, three SLC blocks may be required to move 150 pages of data storedat the selected TLC block, and one SLC block (e.g., SB2) may include anempty storage space. Data of the remaining SLC blocks SB0 and SB1 otherthan the SLC block SB2 including an empty storage space may be stored ata specific TLC block together with data of another SLC block (e.g., SB3)which is fully filled by data, at a garbage collection operation. Ifdata of SLC blocks is stored at a TLC block in the above-describedmanner, a TLC block may be fully filled with data. In other words, allword lines of the TLC block may be closed. This may mean that the TLCblock does not include an open word line. On the other hand, data of SLCblocks SB0, SB1, and SB2 at which 150 pages of data stored at a selectedTLC block is stored is at a specific TLC block, an empty storage spacemay exist at the specific TLC block. This may mean that the specific TLCblock includes an open word line.

Herein, in the case that 3-step reprogramming on memory cells connectedwith an nth word line WLn is completed and third programming of 3-stepreprogramming on memory cells connected with an adjacent word line(e.g., WLn+1) is not performed, the nth word line WLn may be called anopen word line. Target threshold voltage distributions of memory cellsconnected with an open word line may be formed when 3-step reprogrammingon memory cells connected with an adjacent upper word line is completed.If 3-step reprogramming on memory cells connected with an adjacent upperword line is not completed, target threshold voltage distributions ofmemory cells connected with an open word line may not be formednormally. For example, memory cells connected with an open word line mayinsufficiently experience coupling caused by memory cells connected withan adjacent upper word line, so that target threshold voltagedistributions of memory cells connected with the open word line are notformed normally. In this case, the probability that data read frommemory cells connected with an open word line is uncorrectable may beincreased.

Thus, it is possible to prevent an open word line from existing at aspecific TLC block by storing data of the remaining SLC blocks SB0 andSB1 other than the SLC block SB2 including an empty storage space, atthe specific TLC block together with data of another SLC block (e.g.,SB3), which is fully filled by data, at a garbage collection operation.

In example embodiments, data of an SLC block (e.g., SB2) having an emptystorage space may be moved to another SLC block or a TLC block togetherwith data of another SLC block having an empty storage space.

FIG. 10 is a flow chart illustrating a read method of a memory systemaccording to another embodiment of the inventive concept. Below, a readmethod of a memory system according to an embodiment of the inventiveconcept will be more fully described with reference to accompanyingdrawings. It is assumed by way of example that a first memory area 1411is formed of memory blocks (hereinafter, referred to as SLC blocks)which store 1-bit data per cell and a second memory area 1412 is formedof memory blocks (hereinafter, referred to as TLC blocks) which store3-bit data per cell.

In operation S310, a memory controller 1200 may receive a read requestfrom an external device (e.g., a host). In operation S320, the memorycontroller 1200 may control a nonvolatile memory device 1400 such thatread requested data is output. The read requested data may be datastored at a TLC block of a second memory area 1412, for example.Alternatively, the read requested data may be data stored at an SLCblock of a first memory area 1411. In example embodiments, the readrequested data may be data stored at a TLC block of the second memoryarea 1412.

In operation S330, while data output from the nonvolatile memory device1400 is transferred to a buffer memory 1240 of the memory controller1200, an ECC circuit 1250 of the memory controller 1200 may perform anerror detecting operation on data output from the nonvolatile memorydevice 1400. At this time, the data output from the nonvolatile memorydevice 1400 may be temporarily stored at the buffer memory 1240 of thememory controller 1200.

In operation S340, whether an error of data output from the nonvolatilememory device 1400 is correctable may be determined. If so, the methodproceeds to operation S350. In operation S350, an error of data outputfrom the nonvolatile memory device 1400 may be corrected. In operationS360, corrected data stored at the buffer memory 1240 may be sent to theexternal device as the read requested data. Afterward, the readoperation may be terminated.

Retuning to S340, if data output from the nonvolatile memory device 1400is uncorrectable or in the case that the number of error bits of thedata output from the nonvolatile memory device 1400 exceeds a reference(e.g., an allowable error bit number of the ECC circuit 1250), themethod proceeds to operation S370. In operation S370, a read retryoperation may be performed. At the read retry operation, a readoperation may be retried under a condition that a read voltage is variedwithin a predetermined number. An exemplary read retry operation isdisclosed in U.S. Patent Publication No. 2010/0322007, the entirecontents of which are hereby incorporated by reference. Whether dataread whenever a read voltage is varied is correctable may be determinedIn the case that data read via the read retry operation isuncorrectable, the method proceeds to operation S380. In operation S380,a read fail flag may be generated. A procedure according to generationof the read fail flag may be variously determined Afterwards, the methodmay be ended.

In the case that data read via the read retry operation is correctable,the method proceeds to operation S390. In operation S390, informationindicating that a TLC block of the second memory area 1412 at which dataoutput from the nonvolatile memory device 1400 is stored is a targetblock of a read reclaim operation may be stored at a queue. As describedabove, the queue may be formed of a part of a buffer memory 1240, andinformation stored at the queue may be referred by a CPU 1230. Theinformation stored at the queue may be stored at the nonvolatile memorydevice 1400 periodically or at a predetermined time. This may beperformed to prevent information stored at the queue from being lost dueto sudden power-off. A read reclaim operation on a TLC block may beperformed based on information stored at the queue, which will be morefully described later herein.

After information indicating that a TLC block of the second memory area1412 at which data output from the nonvolatile memory device 1400 isstored is a target block of a read reclaim operation is stored at thequeue, the method proceeds to operation S350. In operation S350, anerror of data output from the nonvolatile memory device 1400 may becorrected. In operation S360, corrected data stored at the buffer memory1240 may be sent to the external device as the read requested data.Afterward, the read operation may be terminated.

The memory controller 1200 may perform a read reclaim operation based oninformation stored at the queue, which is performed the same asdescribed with reference to FIGS. 8A, 8B, and 9.

FIG. 11 is a flow chart illustrating a read method of a memory systemaccording to still another embodiment of the inventive concept. Below, aread method of a memory system according to an embodiment of theinventive concept will be more fully described with reference toaccompanying drawings. It is assumed as an example that a first memoryarea 1411 is formed of memory blocks (hereinafter, referred to as SLCblocks) which stores 1-bit data per cell and a second memory area 1412is formed of memory blocks (hereinafter, referred to as TLC blocks)which stores 3-bit data per cell.

In operation S410, a memory controller 1200 may receive a read requestfrom an external device (e.g., a host). In operation S420, the memorycontroller 1200 may control a nonvolatile memory device 1400 such thatread requested data is output. The read requested data may be datastored at a TLC block of a second memory area 1412, for example.Alternatively, the read requested data may be data stored at an SLCblock of a first memory area 1411. In example embodiments, the readrequested data may be data stored at a TLC block of the second memoryarea 1412.

In operation S430, while data output from the nonvolatile memory device1400 is transferred to a buffer memory 1240 of the memory controller1200, an ECC circuit 1250 of the memory controller 1200 may perform anerror detecting operation on data output from the nonvolatile memorydevice 1400. At this time, the data output from the nonvolatile memorydevice 1400 may be temporarily stored at the buffer memory 1240 of thememory controller 1200.

In operation S440, whether the number of error bits included in dataoutput from the nonvolatile memory device 1400 is below a reference maybe determined. Herein, the reference may be an allowable error bitnumber of an ECC circuit 1250, an error bit number less than theallowable error bit number, and so on. If the number of error bitsincluded in data output from the nonvolatile memory device 1400 is overthe reference, the method proceeds to operation S450. In operation S450,information indicating that a TLC block of the second memory area 1412at which data output from the nonvolatile memory device 1400 is storedis a target block of a read reclaim operation may be stored at a queue.As described above, the queue may be formed of a part of a buffer memory1240, and information stored at the queue may be referred by a CPU 1230.The information stored at the queue may be stored at the nonvolatilememory device 1400 periodically or at a predetermined time. This may beperformed to prevent information stored at the queue from being lost dueto sudden power-off. A read reclaim operation on a TLC block may beperformed based on information stored at the queue, which will be morefully described later.

After information indicating that a TLC block of the second memory area1412 at which data output from the nonvolatile memory device 1400 isstored is a target block of a read reclaim operation is stored at thequeue, the method proceeds to operation S460. In operation S460, anerror of data output from the nonvolatile memory device 1400 may becorrected. In operation S470, corrected data stored at the buffer memory1240 may be sent to the external device as the read requested data.Afterward, the read operation may be terminated.

The memory controller 1200 may perform a read reclaim operation based oninformation stored at the queue, which is performed the same asdescribed with reference to FIGS. 8A, 8B, and 9.

FIG. 12 is a block diagram schematically illustrating a read reclaimtechnique of a memory system according to an embodiment of the inventiveconcept.

Referring to FIG. 12, a read reclaim operation may be an operation inwhich valid data of a TLC block including page data having the high readfail probability is moved to a new block, and may be performed to securethe integrity of data. In the case of the inventive concept, informationindicating TLC blocks determined as a target block of a read reclaimoperation may be stored at a queue. At a request (e.g., a write request)of a host, a requested operation may be completed, and a part (or all)of valid pages of data of a TLC block may be moved to an SLC block(s)according to information stored at the queue. A transfer of data to anSLC block may be performed via encoding of an ECC circuit 1250 andbuffer programming.

In example embodiments, the amount of data to be transferred to an SLCblock at a host request may be decided in view of a host timeout period.For example, the amount of data to be transferred to an SLC block maycorrespond to a storage capacity of one SLC block. Alternatively, theamount of data to be transferred to an SLC block may correspond to a sumof storage capacities of two SLC blocks. However, the inventive conceptis not limited thereto. Thus, the requested operation and a transfer ofdata to an SLC block may be performed within a host timeout period.

If valid pages of data of a TLC block decided to be a target block of aread reclaim operation are all moved to SLC blocks, as understood fromFIG. 12, a read reclaim operation associated with the TLC block may beprocessed to be completed. Afterwards, data stored at SLC blocks may bestored at a TLC block via a garbage collection operation or a mainprogram operation at another operation, not via the read reclaimoperation. As described with reference to FIG. 9, in the case that oneof SLC blocks programmed via a read reclaim operation includes an emptystorage space, data of the remaining SLC blocks other than the SLC blockincluding an empty storage space may be stored at a TLC block via a mainprogram operation together with data of another SLC block.

Thus, the read reclaim operation of the inventive concept may beperformed over satisfying a host timeout condition. Also, a memorysystem of the inventive concept may prevent an open word line from beinggenerated at a TLC block.

FIG. 13 is a block diagram schematically illustrating a computing systemaccording to an embodiment of the inventive concept. A computing systemmay include a processing unit 2101, a user interface 2202, a modem 2303such as a baseband chipset, a memory controller 2404, and storage medium2505.

The memory controller 2404 may be configured substantially the same asillustrated in FIGS. 2 and 3, and the storage medium 2505 may be formedof a nonvolatile memory device illustrated in FIG. 4. For example, thememory controller 2404 may manage TLC blocks being a target block of aread reclaim operation, select a TLC block according to informationstored at a queue at a specific time (e.g., at a write request of ahost), and control the storage medium 2505 such that valid pages of dataof the selected TLC block are moved to SLC blocks included in anonvolatile memory device. The memory controller 2404 may process a readreclaim operation on the selected TLC block to be completed when validpages of data of the selected TLC block are moved to SLC blocks includedin a nonvolatile memory device.

N-bit data (N being 1 or more integer) processed/to be processed by theprocessing unit 2101 may be stored in the storage medium 2505 throughthe memory controller 2404. In the event that the computing system is amobile device, a battery 2606 may be further included in the computingsystem to supply an operating voltage thereto. Although not illustratedin FIG. 13, the computing system may further comprise an applicationchipset, a camera image processor (CIS), a mobile DRAM, and the like.

FIG. 14 is a block diagram schematically illustrating a solid statedrive according to an embodiment of the inventive concept.

Referring to FIG. 14, a solid state drive (SSD) 4000 may comprisestorage medium 4100 and a controller 4200. The storage medium 4100 maybe connected with the controller 4200 via a plurality of channels, eachof which is commonly connected with a plurality of nonvolatile memories.The controller 4200 may be configured substantially the same asillustrated in FIGS. 2 and 3, and each of nonvolatile memory devices instorage medium 4100 may be formed of a nonvolatile memory deviceillustrated in FIG. 4. For example, the controller 4200 may manage TLCblocks being a target block of a read reclaim operation, select a TLCblock according to information stored at a queue at a specific time(e.g., at a write request of a host), and control the storage medium4100 such that valid pages of data of the selected TLC block are movedto SLC blocks included in a nonvolatile memory device. The controller4200 may process a read reclaim operation on the selected TLC block tobe completed when valid pages of data of the selected TLC block aremoved to SLC blocks included in a nonvolatile memory device.

FIG. 15 is a block diagram schematically illustrating a storage using asolid state drive shown in FIG. 14, and FIG. 16 is a block diagramschematically illustrating a storage server using a solid state driveshown in FIG. 14.

An SSD 4000 according to an embodiment of the inventive concept may beused to form the storage. As illustrated in FIG. 15, the storage mayinclude a plurality of solid state drives 4000 which are configured thesame as described in FIG. 14. An SSD 4000 according to an embodiment ofthe inventive concept may be used to configure a storage sever. Asillustrated in FIG. 16, a storage server includes a plurality of solidstate drives 4000, which are configured the same as described inconnection with FIG. 14, and a server 4000A. Further, it is understoodthat a well-known RAID controller 4000B may be provided in the storageserver.

FIG. 17 is a block diagram schematically illustrating a moviNAND®according to an embodiment of the inventive concept. Referring to FIG.17, a moviNAND® device 5000 may include at least one NAND flash memorydevice 5100 and a controller 5200. The moviNAND® device 5000 may supportthe MMC 4.4 (or, referred to as “eMMC”) standard.

The NAND flash memory device 5100 may be a single data rate (SDR) NANDflash memory device or a double data rate (DDR) NAND flash memorydevice. In example embodiments, the NAND flash memory device 5100 mayinclude NAND flash memory chips. Herein, the NAND flash memory device5100 may be implemented by stacking the NAND flash memory chips at onepackage (e.g., FBGA, Fine-pitch Ball Grid Array, etc.).

The controller 5200 may be configured substantially the same asillustrated in FIGS. 2 and 3, and each of the NAND flash memory chipsmay be formed of a nonvolatile memory device illustrated in FIG. 4. Forexample, the controller 5200 may manage TLC blocks being a target blockof a read reclaim operation, select a TLC block according to informationstored at a queue at a specific time (e.g., at a write request of ahost), and control the NAND flash memory device 5100 such that validpages of data of the selected TLC block are moved to SLC blocks includedin a nonvolatile memory device. The controller 5200 may process a readreclaim operation on the selected TLC block to be completed when validpages of data of the selected TLC block are moved to SLC blocks includedin a nonvolatile memory device.

The controller 5200 may be connected with the NAND flash memory device5100 via a plurality of channels. The controller 5200 may include atleast one controller core 5210, a host interface 5220, and a NANDinterface 5230. The controller core 5210 may control an overalloperation of the moviNAND device 5000. The host interface 5220 may beconfigured to perform an MMC interface between the controller 5200 and ahost. The NAND interface 5230 may be configured to interface between theNAND flash memory device 5100 and the controller 5200. In exampleembodiments, the host interface 5220 may be a parallel interface (e.g.,an MMC interface). In other example embodiments, the host interface 5220of the moviNAND device 5000 may be a serial interface (e.g., UHS-II,UFS, etc.).

The moviNAND® device 5000 may receive power supply voltages Vcc and Vccqfrom the host. Herein, the power supply voltage Vcc (about 3.3V) may besupplied to the NAND flash memory device 5100 and the NAND interface5230, while the power supply voltage Vccq (about 1.8V/3.3V) may besupplied to the controller 5200. In example embodiments, an externalhigh voltage Vpp may be optionally supplied to the moviNAND® device5000.

The moviNAND® device 5000 according to an embodiment of the inventiveconcept may be advantageous to store mass data and may also have animproved read characteristic. The moviNAND® device 5000 according to anembodiment of the inventive concept is applicable to small and low-powermobile products (e.g., devices known by the tradenames Galaxy S, iPhone,etc.).

FIG. 18 is a block diagram schematically illustrating a communicationdevice according to an embodiment of the inventive concept. Referring toFIG. 18, a communication device 6000 may include a communication unit6100, a controller 6200, a memory unit 6300, a display unit 6400, atouch screen unit 6500, and an audio unit 6600. The memory unit 6300 mayinclude at least one DRAM 6310, at least one OneNAND® 6320, and at leastone moviNAND® 6330.

More detailed descriptions of mobile devices are disclosed in U.S.Patent Publication Nos. 2010/0010040, 2010/0062715, 2010/00199081,2010/0309237 and 2010/0315325, the entire contents of which are hereinincorporated by reference.

FIG. 19 is a diagram schematically illustrating systems to which a datastorage device according to embodiments of the inventive concept isapplied.

As illustrated in FIG. 19, a solid state drive including a data storagedevice according to an embodiment of the inventive concept may beapplied to a main server 8100.

FIG. 20 is a block diagram schematically illustrating a memory cardaccording to an embodiment of the inventive concept.

A memory card, for example, may be an MMC card, an SD card, a multiusecard, a micro-SD card, a memory stick, a compact SD card, an ID card, aPCMCIA card, an SSD card, a chip-card, a smartcard, an USB card, or thelike.

Referring to FIG. 20, the memory card may include an interface circuit9221 for interfacing with an external device, a controller 9222including a buffer memory and controlling an operation of the memorycard, and at least one nonvolatile memory device 9207. The controller9222 may be a processor which is configured to control write and readoperations of the nonvolatile memory device 9207. The controller 9222may be coupled with the nonvolatile memory device 9207 and the interfacecircuit 9221 via a data bus and an address bus. The interface circuit9221 may interface with a host via a card protocol (e.g., SD/MMC) fordata exchange between a host and a memory card.

The controller 9222 may be configured substantially the same asillustrated in FIGS. 2 and 3, and the nonvolatile memory device 9207 maybe formed of a nonvolatile memory device as illustrated in FIG. 4. Forexample, the controller 9222 may manage TLC blocks being a target blockof a read reclaim operation, select a TLC block according to informationstored at a queue at a specific time (e.g., at a write request of ahost), and control the nonvolatile memory device 9207 such that validpages of data of the selected TLC block are moved to SLC blocks includedin the nonvolatile memory device 9207. The controller 9222 may process aread reclaim operation on the selected TLC block to be completed whenvalid pages of data of the selected TLC block are moved to SLC blocksincluded in the nonvolatile memory device 9207.

FIG. 21 is a block diagram schematically illustrating a digital stillcamera according to an embodiment of the inventive concept.

Referring to FIG. 21, a digital still camera may include a body 9301, aslot 9302, a lens 9303, a display circuit 9308, a shutter button 9312, astrobe 9318, and the like. The memory card 9331 may include a memorycontroller and a nonvolatile memory device as described in connectionwith FIG. 2. For example, the controller may manage TLC blocks being atarget block of a read reclaim operation, select a TLC block accordingto information stored at a queue at a specific time (e.g., at a writerequest of a host), and control the nonvolatile memory device such thatvalid pages of data of the selected TLC block are moved to SLC blocksincluded in the nonvolatile memory device. The controller may process aread reclaim operation on the selected TLC block to be completed whenvalid pages of data of the selected TLC block are moved to SLC blocksincluded in the nonvolatile memory device.

If the memory card 9331 is a contact type memory card, an electriccircuit on a circuit board may be electrically contacted with the memorycard 9331 when it is inserted in the slot 9302. In the event that thememory card 9331 is a non-contact type memory card, an electric circuiton a circuit board may communicate with the memory card 9331 by wirelessradio-frequency communication.

FIG. 22 is a diagram schematically illustrating various systems to whicha memory card in FIG. 21 is applied.

Referring to FIG. 22, a memory card 9331 may be applied to a videocamera VC, a television TV, an audio device AD, a game machine GM, anelectronic music device EMD, a cellular phone HP, a computer CP, aPersonal Digital Assistant (PDA), a voice recorder VR, a PC card PCC,and the like.

In example embodiment, memory cells can be formed of a variableresistance memory cell. An exemplary variable resistance memory cell anda memory device including the same are disclosed in U.S. Pat. No.7,529,124, the entirety of which is incorporated by reference herein.

In other example embodiments, memory cells can be formed of one ofvarious cell structures having a charge storage layer. Cell structureshaving a charge storage layer include a charge trap flash structureusing a charge trap layer, a stack flash structure in which arrays arestacked at multiple layers, a source-drain free flash structure, apin-type flash structure, and the like.

A memory device having a charge trap flash structure as a charge storagelayer is disclosed in U.S. Pat. No. 6,858,906 and U.S. PatentPublication Nos. 2004/0169238 and 2006/0180851, the entireties of whichare incorporated by reference herein. A source-drain free flashstructure is disclosed in KR Patent No. 673020, the entirety of which isincorporated by reference herein.

A non-volatile memory device and/or a memory controller according to theinventive concept may be packaged using any of various types ofpackaging technologies. Examples of such packaging technologies includePoP (Package on Package), Ball grid arrays (BGAs), Chip scale packages(CSPs), Plastic Leaded Chip Carrier (PLCC), Plastic Dual In-Line Package(PDIP), Die in Waffle Pack, Die in Wafer Form, Chip On Board (COB),Ceramic Dual In-Line Package (CERDIP), Plastic Metric Quad Flat Pack(MQFP), Small Outline (SOIC), Shrink Small Outline Package (SSOP), ThinSmall Outline (TSOP), Thin Quad Flatpack (TQFP), System In Package(SIP), Multi Chip Package (MCP), Wafer-level Fabricated Package (WFP),Wafer-Level Processed Stack Package (WSP), and the like.

While the inventive concept has been described with reference toexemplary embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the present invention. Therefore, it shouldbe understood that the above embodiments are not limiting, butillustrative.

What is claimed is:
 1. A memory system comprising: a nonvolatile memorydevice including a first memory area formed of memory blocks which storen-bit data per cell and a second memory area formed of memory blockswhich store m-bit data per cell, where n and m are different integers;and a memory controller configured to control the nonvolatile memorydevice, wherein the memory controller is configured to execute a readoperation, and to execute a read reclaim operation in which valid dataof a target memory block of the second memory area is transferred to oneor more memory blocks of the first memory area, the target memory blockselected during the read operation, and wherein the read reclaimoperation is processed as complete when all the valid data of the targetmemory block is transferred to the one or more memory blocks of thefirst memory area.
 2. The memory system of claim 1, wherein the readreclaim operation is timewise divided into a plural separately executedparts in which respective portions of the valid data of the targetmemory block are transferred to the one or more memory blocks of thefirst memory area.
 3. The memory system of claim 1, wherein the memorycontroller is configured to execute at least a part of the read reclaimoperation in response to a write request of a host.
 4. The memory systemof claim 1, wherein the memory controller is configured to execute atleast a part of the read reclaim operation after a write operationrequested by a host is completed.
 5. The memory system of claim 4,wherein, in the read reclaim operation, a portion of the valid data istransferred from the target memory block after the write operation iscompleted and before expiration of a timeout period of the host, andwherein a data amount of the portion of the valid data is determinedbased on a time remaining after the write operation is complete untilthe timeout period of the host.
 6. The memory system of claim 1,wherein, in the read reclaim operation, an amount of the valid datacorresponding to a storage capacity of a memory block of the firstmemory area is transferred to a memory block of the first memory areawhen a program operation is requested of the controller.
 7. The memorysystem of claim 1, wherein data stored at the one or more memory blocksof the first memory area is transferred to one memory block of thesecond memory area during a background operation of the memorycontroller.
 8. The memory system of claim 1, wherein the first memoryarea includes the one or more memory blocks and remaining memory blocks,and, wherein the controller is configured execute a background operationwhich includes: transferring data stored in the one or more memoryblocks of the first memory area, excepting any memory block having anempty storage space, to a selected one of the memory blocks of thesecond memory area; and transferring data stored in at least one of theremaining memory blocks, which is devoid of an empty storage space, ofthe first memory area to the selected one of the memory blocks of thesecond memory area, wherein the selected memory block of the secondmemory area does not include an open word line after the transfers ofdata.
 9. The memory system of claim 1, wherein n=1 and m=3.
 10. Thememory system of claim 1, wherein the memory controller includes abuffer memory configured to store queue information indicating thetarget memory block of the second memory area selected during the readoperation.
 11. The memory system of claim 1, wherein the memorycontroller is configured to timewise divide the read reclaim operationinto plural separately executed parts, wherein each part of the readreclaim operation is executed in response to a respective writeoperation request from a host and to satisfy a timeout condition of thehost.
 12. The memory system of claim 11, wherein, in at least one of theparts of the read reclaim operation, an amount of the valid data of thetarget memory block which corresponds to a storage capacity of a memoryblock of the first memory area is transferred to a memory block of thefirst memory area.
 13. The memory system of claim 10, wherein at theread operation, the memory controller is configured to execute asoftware error correction operation on an error of data read from a readmemory block of the second memory area, and to store the queueinformation at the buffer memory indicating the read memory block as thetarget memory block when the data read from the read memory block iscorrectable via the software error correction operation.
 14. The memorysystem of claim 10, wherein at the read operation, the memory controlleris configured to execute a read retry operation when data read from aread memory block of the second memory area is uncorrectable, and tostore the queue information at the buffer memory indicating the readmemory block as the target memory block when the data read from the readmemory block is correctable via the read retry operation.
 15. The memorysystem of claim 10, wherein at the read operation, the memory controlleris configured to store the queue information at the buffer memoryindicating that a read memory block of the second memory area is thetarget memory block when the number of error bits of data read from readmemory block exceeds a reference.
 16. A read reclaim method of a memorycontroller which controls a nonvolatile memory device including firstmemory blocks which store n-bit data per cell and second memory blockswhich store m-bit data per cell, where n and m are different integers,comprising: identifying a memory block among the second memory blocks asa target of a read reclaim operation; and executing the read reclaimoperation by transferring valid data of the memory block identified as atarget of the read reclaim operation to one or more memory blocks amongthe first memory blocks, wherein the read reclaim operation is processedas complete when all the valid data is transferred to the one or morememory blocks among the first memory blocks.
 17. The read reclaim methodof claim 16, wherein a read reclaim operation is timewise divided into aplurality of separately executed parts to avoid a timeout condition of ahost.
 18. The read reclaim method of claim 17, wherein the parts of theread reclaim operation are performed when respective write operationsare requested by a host.
 19. The read reclaim method of claim 17,wherein the parts of the read reclaim operation are performed afterrespective write operations requested by a host are completed.
 20. Theread reclaim method of claim 17, wherein, in at least one of the partsof the read reclaim operation, a portion of the valid data istransferred after a write operation is completed and before expirationof a timeout period of the host.
 21. The read reclaim method of claim17, wherein, in at least one of the parts of the read reclaim operation,an amount of the valid data corresponding to a storage capacity of amemory block among the first memory blocks is transferred.
 22. The readreclaim method of claim 16, further comprising executing a garbagecollection operation in which data stored at the one or more memoryblocks among the first memory blocks is transferred to a memory blockamong the second memory blocks.
 23. The read reclaim method of claim 16,wherein the first memory blocks include the one or more memory blocksand remaining memory blocks, and wherein the method further comprisesexecuting a background operation which includes: transferring datastored in the one or more memory blocks among the first memory blocks,excepting any memory block having an empty storage space, to a selectedone of the memory blocks among the second memory blocks; andtransferring data stored in at least one of the remaining memory blocks,which is devoid of an empty storage space, among the first memory blocksto the selected one of the memory blocks among the second memory blocks,wherein the selected memory block among the second memory blocks doesnot include an open word line after the transfers of data.
 24. The readreclaim method of claim 16, wherein n=1 and m=3.
 25. The read reclaimmethod of claim 16, wherein data provided from the memory controller isstored at the first memory blocks via a buffer program operation, anddata stored at the first memory blocks is stored at the second memoryblocks via a main program operation.
 26. An operating method of a memorycontroller which controls a nonvolatile memory device including firstmemory blocks which store n-bit data per cell and second memory blockswhich store m-bit data per cell, where n and m are different integers,comprising: storing queue information indicating that a second memoryblock is a target memory block of a read reclaim operation when an errorof data read from the second memory block exceeds a reference; upon ahost request, determining whether the target memory block exists basedon the queue information; programming valid data of the target memoryblock in at least one or more memory blocks among the first memoryblocks when the target memory block is determined to exist; andprogramming data stored at the at least one or more memory blocks amongthe first memory blocks in a memory block among the second memory blocksat a garbage collection operation, wherein the read reclaim operation isprocessed as completed when all the valid data of the target memoryblock is programmed in the at least one or more memory blocks among thefirst memory blocks.
 27. The operating method of claim 26, whereinexistence of the target memory block is determined at a write request ofa host.
 28. The operating method of claim 26, wherein the first memoryblocks include the one or more memory blocks and remaining memoryblocks, and wherein the garbage collection operation includes:transferring data stored in the one or more memory blocks among thefirst memory area, excepting any memory block having an empty storagespace, to a selected one of the memory blocks among the second memoryblocks; and transferring data stored in at least one of the remainingmemory blocks, which is devoid of an empty storage space, among thefirst memory blocks to the selected one of the memory blocks among thesecond memory blocks, wherein the selected memory block among the secondmemory blocks does not include an open word line after the transfers ofdata.
 29. The operating method of claim 26, wherein n=1 and m=3.
 30. Theoperating method of claim 29, wherein data read from the second memoryblock is least significant bit (LSB) page data, center significant bit(CSB) page data, or most significant bit (MSB) page data.